.mainmenu{
    background: whitesmoke;
    width: 50px;
    height: 50px;
    float: right;


}

.mainmenu ul{
    margin: 0;
    padding: 0;
    list-style: none;
}

.mainmenu ul li{
    float: right;
    border-left: #27ae60;
    border-right: #27ae60;
    position: relative;
}

.mainmenu ul li:first-child{
    border-left: 0px solid;
}

.mainmenu ul li:last-child{
    border-right: 0px solid;
}

/*图片*/
.mainmenu ul li a{
    color: #fff;
    display: block;
    padding-left: 8px;
    padding-right: 8px;
    padding-top: 8px;
    padding-bottom: 0px;
    text-decoration: none;
}

.mainmenu ul li a:hover{
    background: orange;
}

.mainmenu ul li ul{
    position: absolute;
    left: 9999px;
    background: #27ae60;
    z-index: 9999;
}

.mainmenu ul li:hover ul{
    left: 0;
}

.mainmenu ul li ul li{
    float: none;
    width: 50px;
    border-bottom: 1px solid #2ecc71;
    border-left: 0px solid;
    border-right: 0px solid;
}

.mainmenu ul li ul li a{
    background: #16a085;
    color: #fff;
    padding: 5px 10px;
}

.mainmenu ul li ul li:last-child{
    border-bottom: 0px solid;
}